Self-cleaning litter box

ABSTRACT

A self-cleaning litter box having a base, a litter pan, an upper hood and a lower hood. A rake is used to sweep litter clumps disposed in the litter pan and into a waste box. The rake is inserted and removed without the use of tools in order to clean or replace the rake. Liners inside the litter pan and waste box allow for easy cleaning. In addition, the liners are used to protect against pitting and other potential damage. Sensors detect the presence of a cat inside the litter pan. Upon exit, an actuator receives an output signal for actuating the drive assembly. After a predetermined time delay after receipt of the output signal, the raking cycle commences. The actuator includes a switch to allow the pet owner to vary the length of the pre-determined time delay.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. ProvisionalApplication Serial No. 60/373,435 filed Apr. 18, 2002 titledSelf-Cleaning Litter Pan.

TECHNICAL FIELD OF THE INVENTION

[0002] This invention relates to a litter box, and more particularly, toa self-cleaning litter box for cats.

BACKGROUND OF THE INVENTION

[0003] Most domesticated cats are trained to use litter boxes toeliminate solid and liquid wastes. These litter boxes are sized to holdparticulate litter that absorbs moisture and suppresses odors from thecat waste. After multiple uses of the litter box by the cat, the petowner can manually dump the waste and litter particulate from the litterbox for disposal.

[0004] Because of the unsanitary environment inside the litter box, somepet owners are reluctant to regularly service these litter boxes. Inaddition, pet owners who frequently travel cannot service these litterboxes on a regular bases. Therefore, various forms of self-cleaning catlitter boxes have been devised for automatically cleaning litter boxes.Many of these devices incorporate a motor driven rake that sifts throughthe litter pan to carry or push the litter clumps into a separate wastecontainer. Unfortunately, many of these automatic litter boxes remaindifficult to clean and oftentimes require more maintenance thantraditional (non-automated) litter boxes. For example, over time litterand waste clumps can attach to the rake tines. If litter clumps remainattached to the rake, the litter will harden and decrease theeffectiveness of the rake. Further, the additional clumps attached tothe rake tines will increase the weight of the rake thereby increasingthe load on the motor. As a result, the motor can be damaged. If themotor is battery operated, battery life can be substantially decreased.In addition, because litter clumps remain attached to the rake,undesirable odors will likely result. In order to thoroughly clean therake, the rake should be detached from the litter box. This usuallyrequires the use of tools, is dirty and requires considerable amounts oftime to disassemble and then reassemble.

[0005] In addition, many self-cleaning litter boxes can hold onlylimited amounts of litter. This is especially true of litter boxesincorporating a motor driven rake that sifts through the litter pan. Ifthe litter level inside the pan is too deep, the rake may be unable tosift through the pan and additional power may be required. As a result,if the motor is battery operated, battery life can be considerablydecreased and/or a larger motor may be required. In most instances,providing a larger motor is not an option due to space and costconsiderations. Furthermore, many present rake configurations are noteffectively able to handle deep litter levels because the rake tineslack sufficient strength. Thus, larger tines have been devised toprovide additional strength. However, larger tines result in largersurface areas that contact the caustic litter pan environment. Thiscontact can substantially reduce the usable life of the rake. Becausecats desire to dig and bury their waste inside the litter, there is aneed to overcome the above-mentioned disadvantages in order to provide adeep litter level inside the litter pan.

[0006] Finally, many litter boxes, both non-automated and automated, areineffective in containing litter particulate inside the litter box. Whencats enter or exit the litter box, litter particulate is often scatteredaround the litter box. As a result, the pet owner must manually cleanthe area around with litter box.

SUMMARY OF THE INVENTION

[0007] The present invention relates to a litter box for cats. The literbox is self-cleaning so as to automatically remove waste clumps thatform from cat excretions. The self-cleaning litter box comprises alitter pan for holding a predetermined amount of cat litter, a rake forsifting through the cat litter to remove any waste clumps locatedtherein, a drive assembly for moving the rake through the cat litter,and a base member to support the litter pan and contain the driveassembly. A waste box is located adjacent the front wall to store clumpsof litter carried by the rake. The litter pan is sized to accommodatemultiple cats at one time while also allowing a deep layer of litter tobe stored therein. This allows the cats to dig or scratch the litter. Awaste box is located adjacent the front wall to store clumps of littercarried by the rake.

[0008] During operation, the rake travels through the litter pan tocollect waste clumps and to deposit the collected clumps inside thewaste box. The rake includes a cross support member to support aplurality spaced apart tines. Each tine is mounted on the support bar ata slight angle and are generally parallel with respect to each other. Apair of rake support arms are located on the ends of the cross member

[0009] The rake tines are preferably coated with either a chrome,TEFLON® or nylon coating in order to reduce or eliminate pitting andother damage to tines. Further, the coating prevents residue fromclumping and remaining attached to the rake after the sweeping cycle.The rake is lightweight so that a greater volume of litter can be storedinside the upper pan without damaging the motor.

[0010] A stabilizer bar, mounted in the base, is used to support andtransport a rake support structure. The rake support structure is usedto support the rake during the sweeping cycle. The rake is easilyremoved from the litter box in a simple manner and without the use oftools in order to clean or replace as necessary.

[0011] The rake is moved across the litter pan by a drive assembly thatis preferably contained inside the base and below the litter pan. Thedrive assembly includes a DC motor that is mounted stationary to thebase. The DC motor drives a pair of belts that connect to the stabilizerbar. Thus, when the belts are moved, the stabilizer bar will also move.

[0012] Upon activation of the drive assembly, the rake will sift throughthe litter to collect and push litter clumps toward the waste box. Asthe rake pushes the clumps toward the waste box, the rake tines push theclumps upward along an inclined ramp. As the rake approaches the wastebox, the waste box lid opens so as to receive the waste clumps. Afterthe litter clumps have been deposited inside the waste box, the motorstops and reverses directions so as to return the rake to the rear wallin the same fashion.

[0013] The waste receptacle can optionally be fitted with a removabletray and/or a disposable liner so that the waste receptacle can beemptied in an easy manner. In addition, a litter pan liner can beprovided to fit inside and to protect the interior of the litter pan.Both liners are provided to add additional protection from the corrosiveenvironment of the waste box and litter pan.

[0014] An upper hood and a lower hood are also provided. The lower hoodattaches to the base so as to protect the base and drive assembly fromlitter scatter, cat hair, cat spray, etc.

[0015] The upper hood portion attaches to the lower hood portion toprovide a cover above the litter pan. The upper hood portion contains astorage compartment located on the top surface to store pet supplies orlitter box components such as waste box liners, for example.Additionally, the upper hood portion contains a chamber for housing afilter. A visor portion extends over the waste box to direct odors thatare released from the waste box into the upper hood when the waste boxis opened. The visor can be detached or retracted when access to theinterior is necessary for servicing the litter pan or waste box. Afterservicing the interior, the visor can be re-attached or expanded so asto be mounted above the waste box.

[0016] Rake movement is controlled by sensors that detect the presenceof a cat or foreign object in the box. In operation, once the useractuates the present litter box by actuating the on/off switch, a powerup sweeping cycle occurs after a preset time delay. The rake moves fromthe “home” position, adjacent to the rear wall of the litter pan towardthe waste box. When the rake approaches the waste box, clumps fall offthe rake and into the waste box. The motor and belt drive system reversedirections to return the rake to the home position.

[0017] Once the rake is in the “home” position, sensors located in thelitter chamber detect the presence of a cat. Once it is determined thatthe cat has exited the litter chamber, a delay mechanism delays thesweeping cycle until after a sufficient amount of time has passed topermit the litter clumps to harden. If, after rake movement begins, acat or foreign object enters the litter box, the sensors will detect thepresence and the raking action will stop. In addition, if the rakeencounters a clump or pile of litter that is too large for the rake tomove through the litter box, the rake will return to the home positionuntil the pet owner manually removes the clump.

[0018] The delay mechanism provides for setting the cycle delay timeafter the cat exits the litter chamber. Thus, the pet owner will be ableto select the length of the delay time before the sweeping cyclecommences in order to allow sufficient time to permit the litter clumpsto harden.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a front perspective view of the present invention withthe hood covering the litter pan;

[0020]FIGS. 2a and 2 b are an exploded perspective view illustrating thepresent invention;

[0021]FIG. 3 is a front perspective view of the litter box illustratingthe rake in the storage position with the lower and upper hoods omitted;

[0022]FIG. 4 is a front elevation view of the rake;

[0023]FIG. 5 is a front perspective view of the litter box illustratingthe rake disposed in the litter pan between the front and rear walls;

[0024]FIG. 6 is a perspective view of the litter box illustrating therake on the front wall ramp illustrating the waste box lid opening;

[0025]FIG. 7 is a front perspective view illustrating the base pan anddrive assembly;

[0026]FIG. 8 is a top plan view of the litter pan illustrating thesensor placement;

[0027]FIG. 9 is a side view of the rake disposed inside the litter panshowing the angled rake tines;

[0028]FIG. 10 is a front perspective view illustrating the pan and lowerhood spray proof rim;

[0029]FIG. 11 is a perspective view of the waste box liner;

[0030]FIG. 12 is an exploded perspective view of the ramp and ramp rug;

[0031]FIG. 13 is a section view of the ramp and rug of FIG. 12 takenalong the line 13-13.

[0032]FIG. 14 is an enlarged view of the rug of FIG. 13.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] FIGS. 1-3 illustrate self-cleaning litter box 20. In a preferredembodiment, litter box 20 includes a base 22, a litter pan 24 forholding a supply of litter, a lower hood 26 and an upper hood 28. Litterbox 20 further includes a rake 30 disposed in litter pan 24, a rakesupport assembly 32 to support rake 30, a drive assembly 34 (FIG. 7) tomove the rake while installed in the litter pan, and a waste box 36 toreceive waste clumps from litter pan 24.

[0034] Referring to FIGS. 3 and 4, litter pan 20 is illustratedconnected to base 22 with lower and upper hoods 26 and 28 removed.Referring specifically to rake 30, rake 30 includes a plurality of tines38 attached to a cross support bar 40. Cross support bar 40 includes afirst end 42 having an offset portion 44 and a second end 46 having anoffset portion 48 (FIG. 4) to engage litter pan 24. Cross support barfirst and second ends 42 and 46 each contain a rake arm 50 and 52 tosupport bar 40 when connected to litter box 20. Rake 30 is preferablyfabricated from a metal material such as stainless steel. It should berealized by one of ordinary skill that tines 38 can be fabricated fromany other material, such as plastic, so long as tines 38 have asufficient strength to rake through litter pan 24 without beingdeflected or destroyed. Rake 30 is lightweight in order to reduce theload on the motor (described in detail below). This permits a greatervolume of litter to be stored inside litter pan 24 without having toincrease to size of the motor. Since cats enjoy scratching and diggingthe litter, a deep litter level is desirable.

[0035] A protective coating may be used to protect tines 38 in order toreduce or eliminate pitting or other damage to tines 38. The coating mayinclude, for example, chrome, nylon, or TEFLON®. Furthermore, thecoating acts as a barrier to prevent residue from attaching to the rakeduring operation. Residue collected on rake tines 38 can increase theweight of the rake, which oftentimes can damage the drive motor or evenrequire additional power to move the rake through litter pan 24. Residuecollected on rake tines 38 also prevents the tines from effectivelysifting through the litter, causing excess litter to be removed fromlitter pan 24. In addition, litter will spread unevenly inside pan 24.By having a material that contains a high strength to weight ratio, raketines 38 can be fabricated smaller to reduce the tine surface areacontacting the litter. In a preferred embodiment, tines 38 contain acircular cross section; however, it should be realized by one ofordinary skill that any cross sectional shape can be used includingsquare, oval, teardrop, rectangular, triangular, etc.

[0036] Referring specifically to FIG. 3, a rake support 32 supports rake30 when installed on litter box 20. Rake support assembly 32 includesposts 54 and 56, and post supports 58 and 60. Posts 54 and 56 includeend openings 62 and 64 defining entranceways to hollow interiors 66 and68. Each post 54 and 56 includes a slot 70 and 72, respectively,extending longitudinally along the length of each post to receive crosssupport bar 40. Rake arms 50 and 52 (FIG. 4) are sufficiently sized soas to slideably engage hollow interiors 66 and 68 respectively. Whenrake 30 is connected to posts 54 and 56, gravity acts on the rake tokeep the rake mounted inside hollow interiors 66 and 68. Rake 30 can beremoved from rake support 32 in a simple manner and without the use oftools in order to clean or replace the rake as necessary. To remove rake30, the rake is lifted so that arms 50 and 52 are removed from posts 54and 56. Likewise, to install rake 30, rake arms 50 and 52 are alignedwith openings 62 and 64 and are inserted therein.

[0037] As seen in FIGS. 3 and 6, litter pan 24 includes a bottom wall 74and spaced apart first and second sidewalls 76 and 78, an inclined frontwall 80 (FIG. 6) and a rear wall 82, defining a litter chamber 84.Litter pan 24 has an open top to allow cats to enter and exit chamber 84and is sized to accommodate multiple cats at one time. Each sidewall 76and 78 contains a planar surface 86 and 88 extending along the top ofthe sidewalls to support rake cross support member 40 at offset portions44 and 48 (FIG. 4). As rake 30 sweeps between front and rear walls 80and 82, the rake is supported by surfaces 86 and 88. Planar surfaces 86and 88 contain elevated sections 222-228 to raise rake 30 as it travelsbetween front wall 80 and rear wall 82.

[0038] Litter pan bottom wall 74 includes strengthening members 90extending between litter pan front wall 80 and rear wall 82 to provideadditional strength to bottom wall 74. Members 90 are preferably ribsintegrally molded into bottom wall 74 to prevent warping or sagging. Inaddition, a shoulder 92 extends along sidewalls 76 and 78. Shoulders 92are positioned above bottom wall 74 to indicate the litter fill level.Thus, litter can be filled inside chamber 84 until the litter levelreaches a height adjacent shoulders 92.

[0039] As illustrated in FIG. 2b, a pan liner 94 is provided to fitinside and to protect walls 74-82 of litter chamber 84. The linercontains walls 96-104 and is preferably vacuum molded with a poly vinylchloride (PVC) material. However, other materials may be used includingthose having biodegradable polylactide. Typical prior art litter panliners are fabricated from a polyethylene bag. These bags are typicallyattached loosely to the litter boxes and, if used in conjunction with araking system, the bag can become tangled with the rake tines. A moldedliner provides advantages over polyethylene liners because molded linerswill not tangle with rake tines 38. In addition, as cats scratch anddig, the polyethylene liner may become rearranged. By using liner 94,the pet owner can keep the litter box clean without having to exposelitter box 20 to soap, water or other moisture that might damage theelectrical components. Also, the vacuum formed liner 94 for litter pan24 prevents walls 74-82 from being scratched and worn from the constantmovement of the abrasive litter materials. If walls 74-82 becomescratched, the walls will tend to hold odor and waste.

[0040] Referring to FIGS. 2b and 6, waste box 36 can be seen. Waste box36 is located adjacent litter pan front wall 80 and contains a bottomwall 106, a rear wall 108, a front wall 110, a pair of sidewalls 112 and114 and a lid 116 pivotably mounted to hinge 118. As seen in FIG. 2b,waste box 36 and litter pan 24 are illustrated as being integrallymolded as one piece; however, it should be realized by one of ordinaryskill that waste box 36 can be a separate component attachable to litterpan 24. As will be explained in greater detail below, as rake 30 travelsupward along inclined wall 80 (FIG. 6), lid 116 pivotably opens so thatlitter clumps (not shown) collected by rake 30 during the raking cyclecan be deposited inside waste box 36. Once the litter clumps aredeposited inside waste box 36, the rake returns to rear wall 82 and lid116 closes to seal any odors from the surrounding area.

[0041] As illustrated in FIG. 2b, waste box 36 can optionally include aninner tray 120 that is removable when cleaning or servicing the wastebox. Inner tray 120 includes sidewalls 122 and 124, end walls 126 and128 and a bottom wall 130. Inner tray 120 is configured to be insertedinside waste box 36.

[0042] A disposable waste box liner 132, as illustrated in FIG. 11, canbe optionally used to protect inner tray 120, or, if waste box 36 isbeing used without tray 120, liner 132 can be used to protect waste boxwalls 106-114. Disposable liner 132 contains pleated sidewall portions134 and 136 and end walls 138 and 140 to form a pocket 144 to receiveand hold waste clumps. End walls 138 and 140 each contain a strap orhandle 146 and 148. A top wall or flap portion 150 is also included andis sized to connect and to protect the underside of waste box lid 116from dirt and waste. Flap portion 150 is substantially the samedimension as lid 116 and contains a pocket 152 along the length of thebag to attach to lid edge 116′.

[0043] During installation of waste box liner 132, handles 146 and 148allow the user to open the bag so that pleated sidewalls 134 and 136 canopen to conform to the width of inner tray 120, or waste box 36, if tray120 is not being used. Sidewalls 134 and 136 and handles 146 and 148 aredesigned to tuck in and around inner tray 120 after waste box liner 132is installed.

[0044] When removing liner 132 from waste box 36, waste box lid 116 isopened using a handle 154 (best seen in FIG. 6). Flap 150 is thendisconnected from lid 116 and flap 150 is used to cover pocket 144. Asdiscussed in further detail below, any litter particulate that may existbetween lid 116 and flap 150 will act to hold down the flap over pocket144 to contain odors inside the pocket. Disposable liner 132 can beremoved from waste box 36 by handles 146 and 148. Upon removal, handles146 and 148 can then be used to further seal pocket portion 144 by tyingthe handles together. The liner is a plastic bag, preferably fabricatedfrom polyethylene or a polypropylene material.

[0045] When closed, waste box lid 116 serves as a step or platform toallow the cat to enter litter chamber 84. After the cat exits waste box20, any litter particulate that is attached to the cat's paws mayeventually collect on waste box lid 116. To prevent litter particulatefrom sliding off lid 116 and onto the surrounding floor when lid 116pivotally opens, waste box lid 116 contains openings 156 to receive thelitter particulate. Thus, as lid 116 opens during the raking cycle (FIG.6), any litter particulate that has settled on lid 116 will slide towardopenings 156 and into waste box 36, instead of scattering on thesurrounding floor.

[0046] Referring to FIG. 7, base 22 and drive assembly 34 can be seen.Base 22 includes a front wall 158, a rear wall 160, and a pair ofsidewalls 162 and 164 to house drive assembly 34. In a preferredembodiment, litter pan 24 rests above and is supported by base 22.Litter pan 24 covers and encloses drive assembly 34 to insulateoperational noises during the raking cycle which also preventing injuryto animals or pet owners. In addition, the litter inside litter chamber84 insulates the noise produced during the raking cycle.

[0047] Drive assembly 34 includes an electric motor 166, a first shaft168 connected to a second shaft 170 by belts 172 and 174. A belt andpulley system includes belts 172 and 174 that are supported by pulleys176 located on opposed ends of shafts 172 and 174. While only pulleys176 are illustrated attached to belt 172, it should be realized by thoseof ordinary skill that the identical configuration can be seen in mirrorimage on belt 174. A stabilizer bar 178 attaches to belts 172 and 174 soas to be moved by the belts between walls 158 and 160. In thisconfiguration, both ends of stabilizer bar 178 travel at exactly thesame rate. Stabilizer bar 178 connects to rake post supports 58 and 60and is operable to move between base front wall 158 and rear wall 160.In operation, motor 166 drives first shaft 168 that in turn rotatespulleys 176 to move belts 172 and 174. Motor 166 is a standard DC motorthat can be powered by batteries or by standard household electricity.

[0048] Base 22 includes a groove 180 having groove endwalls 182 and 184and groove sidewalls 186 and 188. Groove 180 extends parallel to basesidewalls 162 and 164 and between base front and rear walls 158 and 160.Groove 180 is sufficiently sized to receive an offset portion 178′ ofstabilizer bar 178 so that as stabilizer bar 178 travels between frontwall 158 and rear wall 160, offset portion 178′ travels inside groove180. Groove sidewalls 186 and 188 prevent stabilizer bar 178 frommovement in the lateral direction between base sidewalls 162 and 164.

[0049] The ends of stabilizer bar 178 extend through slots 198 and 200and are adapted to connect to rake post supports 58 and 60. Thus, whenrake supports 58 and 60 are connected to stabilizer bar 178, thestabilizer bar moves rake 30 (when installed) between litter pan frontwall 80 and litter pan rear wall 82.

[0050] During the raking cycle, stabilizer bar 178 is transported frombase rear wall 158 toward forward wall 160 until stabilizer bar triggersa relay 202. Once relay 202 is triggered, a signal is sent to amicroprocessor (not shown) which in turn sends a signal to motor 166 toreverse the direction of stabilizer bar 178 in the direction of baserear wall 158. If however, relay 202 fails, offset portion 178′ willcontact groove end wall 182 to prevent the stabilizer bar from travelingfurther and potentially damaging other components, such as shaft 168Likewise, as stabilizer bar nears base rear wall 158, stabilizer bar 178will trigger relay 204 to send a signal to shut off motor 166. If relay204 fails, offset portion 178′ will contact groove end 184 so as toprevent further movement of stabilizer bar 178.

[0051] Referring to FIGS. 3, 4 and 8, rake movement is partiallycontrolled by sensors 206 and 208 that detect the presence of a cat orforeign object in the box. Sensors 206 and 208 preferably includeinfrared photocell detectors that detect when a beam has been disturbedor broken. Sensors 206 and 208 each include a transmitter designated bythe letter “T” and a detector or receiver, designated by the letter “R”.As illustrated in FIG. 8, transmitter 206T and receiver 208R aredisposed along litter pan sidewall 76. A receiver 206R is also disposedalong litter pan sidewall 78 and is aligned with transmitter 206T.Transmitter 208T is disposed on sidewall 78 opposite receiver 208R.Receivers 206R and 208R, which detect signals generated by transmitters206T and 208T, operate to detect the presence of a cat or a foreignobject within the litter chamber 84. It should be realized by one ofordinary skill that a greater or fewer number of photo cell detectorscan be used if litter chamber 24 is larger or smaller.

[0052] Transmitters 206T and 208T are disposed on opposite sidewalls 76and 78 to prevent transmitter 206T from interfering with receiver 208Rand to prevent transmitter 208T from interfering with receiver 206R. Inthis configuration, transmitter 206T is independent of transmitter 208T;therefore, when rake 30 enters the beam spread area 206B for transmitter206T, transmitter 208R will remain operable to detect cats or otherobstructions. The same is true when rake 30 enters beam spread area208B. In order to permit the litter pan sensors to detect objects in thewidest area inside litter chamber 84, transmitters 206T and 208T arespaced apart so that beam spread areas 206B and 208B are adjacent eachother or have minimal overlap, as seen in FIG. 8.

[0053] In operation, the user supplies power to litter box 20 byactuating an on/off switch (not shown). An initial “power up” rake sweepcycle begins after a set time delay. Rake 30 begins the sweep cycle bymoving from the “home position,” located adjacent litter pan rear wall82 (FIGS. 3 and 9), and continuing through the middle portion of litterchamber 84 (FIGS. 5 and 9) toward inclined front wall 80. During thistime, any litter clumps (not shown) present in litter chamber 84 arepushed toward inclined front wall 80. Once rake 30 reaches inclinedfront wall 80, rake 30 pushes the litter clumps (not shown) upward alonginclined front wall 80, as best seen in FIG. 6. As rake 30 travelsupward along inclined wall 80, lid ramps 210 and 212 engages rollers 214and 216, located on ear ears 218 and 220. Ears 218 and 220 are attachedto waste box lid 116 so that as rollers 214 and 216 travel upward alonglid ramps 210 and 212, lid 116 will pivotably open. During this time,cross member 40 is pushed upward by planar surface ramps 222 and 224 sothat rake arms 50 and 52 (FIG. 4) raise inside and slideably engagedhollow interiors 66 and 68. As rake 30 travels to the uppermost portionof inclined wall 80 and planar surface ramps 222 and 224, the litterclumps will fall off rake 30 into the waste box 36. Movement of rake 30is terminated at the top end of inclined front wall 80 when the positionof stabilizer bar 178 is detected by relay 204 (FIG. 7). When relay 204is triggered, a signal is sent to a microcontroller which in turn sendsa signal to motor 166 to reverse directions to move rake 30 to the“home” position (FIG. 3). Upon approaching litter pan rear wall 82,movement of rake 30 is terminated when the stabilizer bar position isdetected by relay 202 (FIG. 7).

[0054] As seen specifically in FIG. 9, tines 38 are angularly disposedwith respect to rake arms 50 and 52. This angled configuration permitsthe waste clumps to gravitally fall from rake 30 into waste box 36.

[0055] Referring back to FIG. 3, sidewall planar surfaces 86 and 88include ramps 226 and 228 which are inclined to lift rake 30 upward asthe rake approaches litter pan rear wall 82. In addition, litter panbottom wall 74 includes a ramp 230. This configuration ensures that rake30 can continue to travel to and from the home position to overcome thenatural buildup of litter that occurs adjacent rear wall 82. Litterbuildup occurs as a result of rake 30 traveling to the “home” position.In addition, at the commencement of the raking cycle, the inclinedplanar surface ramps 226 and 228 and bottom wall ramp 230 enable rake 30to gradually dig “down” into the litter as rake 30 travels towardinclined front wall 80 along ramp 230. Ramps 226 and 228 aresufficiently sized to raise rake 30; however, tines 38 still remainbelow the top surface of the litter level.

[0056] After the initial power up sweep, as described above, litter box20 is ready for use. When the cat enters litter chamber 84, sensors 206and/or 208 detect the presence of the cat. Once sensors 206 and/or 208detect that the cat has exited litter chamber 84, a signal is sent to atimer to delay the commencement of the sweeping cycle after apredetermined delay period. A switch 232 (FIG. 7) can be optionallyprovided to allow the pet owner to determine the predetermined length ofthe delay period before commencing the sweeping cycle. In a preferredembodiment, switch 232 is a three position switch that allows the petowner to set the delay period for either ten, fifteen or twenty minutesas some litter clumps require different time lengths to sufficientlyharden before being swept by rake 30. In the alternative, a remotecontrol 280 (FIG. 1) can include a switch 232 to permit the pet owner toselect the predetermined delay period. When the delay period expires,sensors 206 and 208 confirm that no cat or foreign object is present inlitter chamber 84. If a cat or foreign object is detected, rakingoperation will not start. If no cat or foreign object is detected, rakemoves forward until reaching waste box 36. Upon reaching waste box 36,rake 30 stops to permit the litter clumps to fall inside waste box 36.After a short period of time elapses, rake 30 then reverses directions,as previously described, and returns to the “home” position (FIG. 3).During the raking cycle, sensors 206 and 208 continue to detect whethera cat or foreign object has entered litter chamber 84. If, during theraking cycle, a cat or foreign object is detected, the raking sequencestops until the cat or foreign object is no longer in litter chamber 84.

[0057] A motor load sensor (not shown) will detect if rake 30 encountersa waste clump or pile of litter that is too great to be moved by therake. Motor load sensor operates by monitoring the load on motor 166such that when the load across the motor reaches a predetermined value,a signal will be sent to the microcontroller which in turn sends asignal to reverse the direction of motor 166 to return rake 30 to eitherlitter pan front wall 80 or litter pan rear wall 82, whichever is in thereverse direction of the path. Rake 30 will then reverse direction andtravel toward the waste clump in an additional attempt to move theclump. If after multiple attempts the clump cannot be moved, the petowner will be alerted that litter box 20 requires maintenance.

[0058] As can be best seen in FIG. 9 rake tines 38 extend downward andare located adjacent bottom wall 74. A slight gap G extends betweentines 38 and bottom wall 74 to prevent rake from scratching floor 74.However, gap G should be a minimal distance so as to prevent litterclumps from remaining inside the bottom of litter chamber 84.

[0059] As seen in FIG. 10, lower hood 26 is installed to surround litterpan 24. Hood 26 includes a forward wall 234, a pair of sidewalls 236 and238, and a rear wall 240 to surround and protect litter pan 24 and base22. Lower hood 26 is mounted on hood supports 242 and 244 and is lockedto base 22 with latch 246 (additional hood supports 242 and 244 andlatch 246 are also located in mirror image along sidewall 236).

[0060] As can be seen, lower hood sidewalls 236 and 238 conceal rakesupports 58 and 60, posts 54 and 56, and lid ramps 210 and 212. Byconcealing these moving elements, the litter box 20 is maintained cleanand better protected from litter, cat hair, spray, etc.

[0061] Interior sidewalls 248 and 250 and rear wall 252 are a sufficientheight above litter pan 24 to protect the areas surrounding the litterpan from litter scatter and cat spray. In addition, a rim 254 extendingalong interior walls 248 and 250 cover cross member offset portions 44and 48 (offset portions best seen in FIG. 4). A rim 256 also extendsalong rear wall 252. Rims 254 and 256 reduce spray and litter scatterthat may damage the moving elements described above.

[0062] In addition to reducing litter scatter and spray, rims 254prevent rake 30 from rising above and separating from planar surface 86and 88. During the raking cycle, rake 30 tends to rise up as it movesthrough the litter. Thus, the shape of rims 254 correspond to the shapeof planar surfaces 86 and 88 and are sufficiently spaced apart such thatcross support bar offset portions 44 and 48 can be placed between rims254 and planar surfaces 86 and 88. This prevents rake 30 from risingabove planar surfaces 86 and 88 during the raking cycle. Latches 246 areused to secure lower hood 26 to base 22 to prevent rake 30 from pushinghood 26 upward.

[0063] When it is desired to remove rake 30 from litter box 20, lowerhood 26 is detached from base 22 by unlocking latches 246. Onceunlocked, lower hood 26 is lifted away from base 22 thereby exposingrake offset portions 44 and 48 being connected to rake supports 32. Aspreviously explained, rake 30 is lifted so that arms 50 and 52 areremoved from posts 54 and 56. To install rake 30 in litter box 20, rakearms 50 and 52 are aligned with openings 62 and 64 and inserted therein.Hood 26 is then re-attached to base 22 and locked by latches 246.

[0064] As seen in FIGS. 1 and 12, an entrance ramp 258 can be attachedto litter box 20 to allow a cat to easily enter and exit litter chamber84. Ramp 258 is removable such that litter box 20 can be used with orwithout the ramp. A rug 260 can be used to overlay ramp 250 to catch anylitter that is spread when the cat exits litter chamber 84.

[0065] Referring to FIGS. 13 and 14, rug 260 includes a backing layer262 and a twisted fabric loop material 264 attached the backing layer.Twisted fabric loop material 264 is preferably a twisted cotton loopthat is approximately 1-1.25 inches in length. Twisted loops 264 arespaced apart such that litter can be trapped between each fabric loopmaterial 264. This prevents litter from scattering on the surroundingfloor area. Alternatively, twisted fabric loop material 264 may besubstituted for twisted, but non-looped material, if desired.

[0066] Rug backing 262 contains a plurality of elastic loops 266 (FIG.12) attached to backing 262 so that rug 260 can be easily attached tohooks 268 on ramp 258. In addition to being attachable to ramp 258, rug260 can be sufficiently sized overlay the floor area surrounding oradjacent to litter box 20. Multiple sections can be attachable together,using a hook and pile fastener for example, to protect the surroundingareas.

[0067] Referring back to FIGS. 1 and 2a, upper hood 28 is used to coverlitter pan 20. It should be realized by one of ordinary skill thatlitter box 20 can be used without upper hood 28 if it is desired tooperate as a “non-hooded” or an “open” litter box. Hood 28 includes aremovable visor portion 270 located above waste box 36. Visor portion270 extends over waste box 36 so that as waste box lid 116 opens, odorswill be directed by visor portion 270 into hood 28. A filter 272 ismounted to hood 28 toward the rear portion of litter box 20. Thus, odorsthat rise from litter chamber 84 or those that are released from wastebox 36, when open, can be filtered by filter 272. The filter is mostpreferably a polyester substrate with charcoal and zeolite particlesstored in a polyethylene bag.

[0068] Visor portion 270 can be completely detached from hood 28 (asseen in FIG. 2a) to allow access to waste box 36 without detaching hood28 entirely from litter box 20. In the alternative, visor portion 270can be pivotably mounted to hood 28 so that it remains attached at alltimes; thus when it is desired to access waste box 36, visor portion 270can be pivotably opened. Visor portion 270 is preferably fabricated froma translucent or transparent, but slightly tinted material, so that theconsumer can view litter chamber 84 while also providing the catsufficient privacy.

[0069] In addition, hood 28 includes a storage compartment 274 that issized to receive and store pet supplies such as replacement waste boxliners. Storage compartment 274 contains a lid 276 that can be openedfor easy access inside storage compartment 274. The pet owner can removelid 276 to gain access inside interior 274 by using finger grips 277 tocompletely lift lid 276 away from hood 28. Hood 28 also can optionallyinclude a storage compartment or receiving area 278 for holding remotecontrol 280 (FIG. 1) to operate litter box 20.

[0070] Other alterations and modifications of the invention willlikewise become apparent to those of ordinary skill in the art uponreading the present disclosure, and it is intended that the scope of theinvention disclosed herein be limited only by the broadestinterpretation of the appended claims to which the inventors are legallyentitled.

We claim:
 1. A rake for a litter box for collecting pet excrements, thelitter box containing a bottom surface, a front wall, a rear wall afirst and second sidewall to define a litter chamber for holding asupply of litter, the rake comprising: a bar having first and secondends and from the first sidewall to the second sidewall and movablebetween the front and rear walls, said bar including a plurality oftines; rake support attached to said bar for supporting said first andsecond ends of said bar for slideable movement between the front andrear walls; and a rake arm connected to said first and second ends ofsaid bar for slideably engaging said rake supports such that said bar isselectively connectable to said rake supports without using fasteners.2. The rake of claim 1 wherein said tines comprise metal.
 3. The rake ofclaim 2 wherein said tines comprise a chrome coating.
 4. The rake ofclaim 2 wherein said tines comprise a TEFLON® coating.
 5. The rake ofclaim 2 wherein said tines comprise a nylon coating.
 6. The rake ofclaim 1 wherein said tines comprise plastic.
 7. The rake of claim 6wherein said tines include a chrome coating.
 8. The rake of claim 6wherein said tines include a TEFLON® coating.
 9. The rake of claim 6wherein said tines include a nylon coating.
 10. The rake of claim 1wherein said rake supports include a post having a hollow interior andan aperture for receiving said rake arm portion by gravitational forces.11. The rake of claim 10 wherein said rake arms frictionally engage saidpost hollow interiors.
 12. The rake of claim 1 wherein said plurality oftines are angularly disposed to said rake supports when said bar issupported by said rake support.
 13. A litter box comprising: a chamberhaving a bottom wall, spaced apart front and rear walls and first andsecond side walls for retaining a supply of litter; a first sensor fordetecting an obstruction in said litter chamber, said first sensorhaving a transmitter and a receiver wherein said transmitter generatesan output signal that is detected by said receiver, said transmitterbeing disposed on said first sidewall and said first receiver beingdisposed on said second sidewall; and a second sensor spaced apart fromsaid first sensor for detecting an obstruction in said litter chamber,said second sensor having a transmitter and a receiver wherein saidtransmitter generates an output signal that is detected by said secondreceiver, said second transmitter is disposed on said second sidewalland said second receiver is disposed on said first sidewall.
 14. Thelitter box of claim 13 wherein said first and second transmitters eachgenerate an infrared output signal transversing an area such that saidareas are non-overlapping and disposed adjacent each other.
 15. Thelitter box of claim 13 wherein said first and second receivers areinfrared photocell detectors.
 16. An automatic cleaning litter box forcollecting cat excretions, the litter box comprising: a litter panhaving an open top, a bottom wall, a front wall, a rear wall and a pairof sidewalls; a rake disposed in said pan and extending between saidsidewalls, said rake being movable between said front wall and said rearwall; a drive assembly for driving said rake from said rear wall to saidfront wall to remove the excretions from said pan; a sensor forgenerating an output signal upon detection of a cat exiting said pan; anactuator for receiving said output signal for actuating said driveassembly after a predetermined time delay after receipt of said outputsignal; and said actuator including means for adjusting saidpredetermined time delay.
 17. A litter box for collecting catexcretions, the litter box comprising: a litter pan having an open top,a bottom wall, a rear wall, a front wall and a pair of sidewalls; awaste box disposed adjacent said litter pan for storing cat excretions;a hood disposed adjacent said litter pan to cover said litter pan opentop; and said hood including a portion operable between first and secondpositions, such that in said first position, said portion overhangs saidwaste box to direct odors from said waste box into said hood, andwherein in said second position, said portion allows access to saidwaste box without removing said hood.
 18. The litter box of claim 17wherein said hood includes a filter and when said portion is in saidfirst position, odors from said waste box are directed to said filter.19. An automatic cleaning cat litter box for collecting cat excretions,the litter box comprising: a litter pan having an open top, a bottomwall, a front wall, a rear wall and a pair of sidewalls, a rake disposedin said pan, said rake having a bar extending between said sidewalls,said bar including a plurality of tines; a drive assembly for drivingsaid rake from said rear wall to said front wall so as to removeexcretions from said pan; and an inclined portion adjacent said rearwall, such that when said rake travels from said front wall to said rearwall, said inclined portion causes said rake to move above said bottomwall.
 20. The automatic cleaning litter box of claim 19 wherein saiddrive assembly includes an electric motor attached to a belt for movingsaid rake between said litter pan front wall and said rear wall.
 21. Anautomatic cleaning litter box comprising: a litter pan having an opentop, a bottom wall, a front wall, a rear wall a first sidewall and asecond sidewall; a rake disposed in said litter pan and moveable betweensaid litter pan front and rear walls, said rake having a bar extendingbetween said sidewalls and having first and second support arms; a basehaving an open top, a bottom wall, a front wall, a rear wall, and a pairof sidewalls for supporting said litter pan; a drive assembly disposedin said base, said drive assembly including a motor and a stabilizer barfor moving said rake between said litter pan front and rear walls; and arake support for moving said rake between said pan front and rear walls,said rake support including a post support connected to said stabilizerbar, said post support including first and second posts adapted toreceive said rake first and second arms.
 22. The automatic cleaninglitter box of claim 21 wherein said drive assembly includes a motor anda belt and pulley system for moving said stabilizer bar between saidbase front and rear walls.
 23. The automatic cleaning litter box ofclaim 22 wherein said base bottom wall includes a groove extendingbetween said base front and rear walls, said groove adapted to receive aportion of said stabilizer bar to prevent movement of said stabilizerbar between said base sidewalls.
 24. The automatic cleaning litter boxof claim 21 wherein said rake arms slideably engage said posts such thatsaid rake is selectively connectable to said rake support without usingfasteners.
 25. The automatic cleaning litter box of claim 21 whereinsaid litter pan sidewalls include a top planar surface extending betweensaid front wall and said rear wall, said rake is supported by saidplanar surface as said rake travels between said litter pan front andrear walls.
 26. The automatic cleaning litter box of claim 25 includinga hood disposed adjacent said litter pan rear wall and sidewalls adaptedto hold said bar along said sidewall planar surfaces as said raketravels between said litter pan front and rear walls.
 27. The automaticcleaning litter box of claim 21 and further including a hood disposedadjacent said litter pan rear wall and sidewalls, said hood including arim extending into said litter pan to prevent litter debris and urinefrom entering said base pan.
 28. The automatic cleaning litter box ofclaim 21 wherein said litter pan bottom wall includes members forstrengthening said bottom wall.
 29. The automatic cleaning litter box ofclaim 28 wherein said strengthening members include ribs.
 30. Theautomatic cleaning litter box of claim 21 wherein said litter pan bottomwall includes an inclined ramp adjacent said rear wall to prevent thebuildup of litter along the litter pan rear wall.
 31. The automaticcleaning litter box of claim 21 wherein said litter pan includes: afirst sensor for detecting an obstruction in said litter pan, said firstsensor having a transmitter and a receiver wherein said transmittergenerates an output signal that is detected by said receiver, saidtransmitter being disposed on said first sidewall and said firstreceiver being disposed on said second sidewall; and a second sensorspaced apart from said first sensor for detecting an obstruction in saidlitter chamber, said second sensor having a transmitter and a receiverwherein said transmitter generates an output signal that is detected bysaid second receiver, said second transmitter is disposed on said secondsidewall and said second receiver is disposed on said first sidewall.32. The automatic cleaning litter box of claim 31 wherein said saidfirst and second transmitters each generate an infrared output signaltransversing an area such that said areas are non-overlapping anddisposed adjacent each other.
 33. The automatic cleaning litter box ofclaim 32 wherein said first and second receivers are infrared photocelldetectors.
 34. The automatic cleaning litter box of claim 21 and furtherincluding a waste box disposed adjacent said litter pan front wall toreceive litter clumps collected from said litter pan and to collectlitter particulate scattered onto said waste box after a cat exits theautomatic cleaning litter box, the waste box comprising: a bottom wall,a pair of sidewalls, a pair of end walls and a pivotable top forming awaste storage area, said top movable between closed and openedpositions, such that as said rake moves to said front wall, said topmoves to said open position; and said waste box pivotable top includesan opening to direct the scattered litter particulate present on saidwaste box pivotable top into said waste storage area as said waste boxpivotable top moves to said open position.
 35. The waste box of claim 34and further including a removable litter tray disposed inside said wastebox.
 36. The waste box of claim 35 and further including a protectiveliner disposed in said removable litter tray.
 37. The protective linerof claim 35 wherein said liner includes a pair of sidewalls and a pairof end walls wherein said walls form a pocket having an opening toreceive the litter clumps.
 38. The protective liner of claim 37 whereinsaid liner includes a flap portion to cover said pocket opening, saidflap portion being adapted to connect to said waste box pivotable top toclose and open said pocket as said pivotable top moves between saidclosed and open positions.
 39. The protective liner of claim 37 whereinsaid liner includes a pair of handles to remove said liner from saidwaste box and to seal said pocket.
 40. The automatic cleaning litter boxof claim 34 wherein a hood is disposed adjacent said litter pan to coversaid litter pan open top, said hood including a portion operable betweenfirst and second positions, such that in said first position, saidportion overhangs said waste box to direct odors from said waste boxinto said hood, and wherein in said second position, said portion allowsaccess to said waste box without removing said hood.
 41. The automaticcleaning litter box of claim 40 wherein said hood includes a filter andwhen said visor is in said first position, odors from said waste box aredirected to said filter.
 42. The waste box of claim 34 and furtherincluding a protective liner disposed in said waste storage area. 43.The protective liner of claim 42 wherein said liner includes a pair ofsidewalls and a pair of end walls wherein said walls form a pockethaving an opening to receive the litter clumps.
 44. The protective linerof claim 43 wherein said liner includes a flap portion to cover saidpocket opening, said flap portion being adapted to connect to said wastebox pivotable top to close and open said pocket as said pivotable topmoves between said closed and open positions.
 45. The protective linerof claim 44 wherein said liner includes a pair of handles to remove saidliner from said waste box and to seal said pocket.
 46. The automaticcleaning litter box of claim 21 having a liner disposed in said litterpan to protect said bottom wall, said front wall, said rear wall, saidfirst and second sidewalls.
 47. The liner of claim 46 wherein said lineris fabricated from poly vinyl chloride.
 48. A waste box for use with alitter box, the waste box used for collecting litter clumps removed fromthe litter box and for collecting litter particulate scattered onto thewaste box after a cat exits the litter box, the waste box comprising: abottom wall, a pair of sidewalls, a pair of end walls and a pivotabletop forming a waste storage area, said top movable between closed andopened positions; and said waste box pivotable top includes an openingto direct the scattered litter particulate present on said waste boxpivotable top into said waste storage area as said waste box pivotabletop moves to said open position.
 49. The waste box of claim 48 andfurther including a removable litter tray disposed inside said waste boxto receive litter clumps from the automatic cleaning litter box.
 50. Thewaste box of claim 49 and further including a liner disposed in saidlitter tray.
 51. The waste box of claim 50 and further including aprotective liner disposed in said removable litter tray.
 52. Theprotective liner of claim 51 wherein said liner includes a pair ofsidewalls and a pair of end walls wherein said walls form a pockethaving an opening to receive the litter clumps.
 53. The protective linerof claim 52 wherein said liner includes a flap portion to cover saidpocket opening, said flap portion being adapted to connect to said wastebox pivotable top to close and open said pocket as said pivotable topmoves between said closed and open positions.
 54. The protective linerof claim 53 wherein said liner includes a pair of handles to remove saidliner from said waste box and to seal said pocket.
 55. The waste box ofclaim 58 and further including a protective liner disposed in said wastestorage area.
 56. The protective liner of claim 55 wherein said linerincludes a pair of sidewalls and a pair of end walls wherein said wallsform a pocket having an opening to receive the litter clumps.
 57. Theprotective liner of claim 56 wherein said liner includes a flap portionto cover said pocket opening, said flap portion being adapted to connectto said waste box pivotable top to close and open said pocket as saidpivotable top moves between said closed and open positions.
 58. Theprotective liner of claim 56 wherein said liner includes a pair ofhandles to remove said liner from said waste box and to seal saidpocket.
 59. In a litter box including a ramp, a rug for the rampcomprising: a backing for supporting a plurality of twisted fabric loopportions, wherein said twisted fabric loop portions are spaced apart asufficient length to allow litter to be trapped between the loops alongthe ramp.
 60. The rug of claim 59 wherein said length of each of saidloop portions is about 0.5 inches.
 61. The rug of claim 60 wherein saidtwisted fabric loop portion is selected from the group consisting ofnylon and cotton.
 62. The lifter box of claim 17 wherein said portion istranslucent to allow viewing inside said lifter pan.